When fabricating Perpendicular Magnetic Recording (PMR) writer main poles (hereafter referred to simple as “PMR poles”), generally a trapezoidal shaped trench is etched into a thick substrate layer (e.g., alumina) and the trench is then filled with a magnetic material by way of a plating process. It has been shown that during fabrication, lining the inside of the trench and cover the top surface of the thick substrate layer with a plating seed layer can achieve a substantially void-free fill of the trench (with the magnetic material) while retaining desirable properties (e.g., as high saturation magnetization, low easy/hard axis coercivity, low anisotropy, high frequency response, and low remnant magnetization).
Using ruthenium (Ru) when plating high moment magnetic materials, such as those used in PMR poles, is known to provide the high moment magnetic materials with desirable properties for effective functioning of the magnetic head. Additionally, it can be useful and desirable to encapsulate the PMR pole with a soft magnetic shield, where the soft magnetic shield is plated over the top and sides of the PMR pole with an intervening non-magnetic spacer layer that also serves as a plating seed. Like with high momentum magnetic materials, Ru is well suited for the plating of soft high moment magnetic materials. Of known deposition techniques, Chemical Vapor Deposition (CVD) is one commercially viable method for providing conformal Ru deposition, and is often used for electroplating seed layers during PMR pole fabrication.
Unfortunately, it is a challenge to form a smooth, highly conformal layer of Ru on the inside of the trench or the exposed surfaces of the three dimensional PMR pole structure while also providing good thickness control and uniformity over the entire PMR pole structure. Additionally, employing a Chemical Vapor Deposition (CVD) Ru-based film as a Ru layer is known to cause peeling/delamination issues during plating processes or chemical mechanical polishing (CMP). This is especially true where the CVD Ru-based film is deposited from RuO4-containing precursor and where the CVD-Ru-based film is deposited on a dielectric, such as an amorphous seed layer.